AD	Adult Disease
AGREE II	The Appraisal of Guidelines for Research and Evaluation II Tool
ALD	Adrenoleukodystrophy
AMSTAR 2	A Measurement Tool to Assess Systematic Reviews
ARSA	Arylsulfatase A
ARSA-PD	Arylsulfatase A Pseudodeficiency
CNS	Central Nervous System
DBS	Dried Blood Spot
DUS	Dried Urine Spot
EJ	Early Juvenile
FPR	False Positive Rate
GRADE	Grading of Recommendations, Assessment, Development, and Evaluation
HSCT	Hematopoietic Stem Cell Transplantation
LI	Late Infantile
LJ	Late Juvenile
LC-MS/MS	Liquid Chromatography—Tandem Mass Spectrometry
MLD	Metachromatic Leukodystrophy
MoM	Multiples of Median
MRI	Magnetic Resonance Imaging
MSD	Multiple Sulfatase Deficiency
NBS	Newborn Screening
NGS	Next Generation Sequencing
NOS	Newcastle–Ottawa Scale
QUADAS-2	Quality Assessment of Diagnostic Accuracy Studies 2
VUS	Variants of Uncertain Significance
WES	Whole-Exome Sequencing